add unmaintained message to all .mds for #1466

CHANGELOG.md

@@ -1,4 +1,20 @@
-# ksh 2020.1.0 (this is a work in progress)
+# This branch is not supported
+
+This branch contains the **ksh2020** version of the AST tools, from January
+2020, which primarily written and maintained by @krader1961 and @siteshwar.
+
+This branch is not supported or maintained by AT&T; the repo at
+https://github.com/att/ast only officially hosts ksh93u+ and the experimental
+ksh93v- branch.
+
+See [#1464](https://github.com/att/ast/issues/1464) and
+[#1466](https://github.com/att/ast/issues/1466) for discussion and history of
+ksh2020 leaving the github/att organization.
+
+Please search for forks of this repo if you are looking for ksh2020.
+
+
+#ksh 2020.1.0 (this is a work in progress)
 
 ## Deprecations
 

CONTRIBUTING.md

@@ -1,3 +1,19 @@
+# This branch is not supported
+
+This branch contains the **ksh2020** version of the AST tools, from January
+2020, which primarily written and maintained by @krader1961 and @siteshwar.
+
+This branch is not supported or maintained by AT&T; the repo at
+https://github.com/att/ast only officially hosts ksh93u+ and the experimental
+ksh93v- branch.
+
+See [#1464](https://github.com/att/ast/issues/1464) and
+[#1466](https://github.com/att/ast/issues/1466) for discussion and history of
+this decision.
+
+Please search for forks of this repo if you are looking for ksh2020.
+
+
 # Guidelines for Developers
 
 This document provides guidelines for making changes to the AST Korn shell

README.md

@@ -1,3 +1,19 @@
+# This branch is not supported
+
+This branch contains the **ksh2020** version of the AST tools, from January
+2020, which primarily written and maintained by @krader1961 and @siteshwar.
+
+This branch is not supported or maintained by AT&T; the repo at
+https://github.com/att/ast only officially hosts ksh93u+ and the experimental
+ksh93v- branch.
+
+See [#1464](https://github.com/att/ast/issues/1464) and
+[#1466](https://github.com/att/ast/issues/1466) for discussion and history of
+this decision.
+
+Please search for forks of this repo if you are looking for ksh2020.
+
+
 # KSH93
 
 This repository contains the AT&T Software Technology (AST) toolkit